This invention relates to fluids comprising water and a mist suppressing copolymer. Optionally, the fluid can be an oil-in-water emulsion, including oil and an emulsifier. In addition to the mist suppressing copolymer, metal cutting operations and other high-shear operations often involve a work piece which rotates at relatively high speed, and a cutting tool, both of which are lubricated by a metal working fluid. Under these conditions, the metal working fluid is frequently thrown from the surface of the metal in the form of droplets. Often the droplets are small enough to be classified as a mist. Misting, or the formation of a mist, is considered undesirable because it represents a loss of the cutting fluid and because the cutting fluid mist is considered a contaminant in the air around the cutting machine.
Various polymers are known to thicken aqueous materials.
European Patent Application EP 811 677, published Dec. 10, 1997, discloses aqueous metal working fluids containing a mist suppressing copolymer which includes hydrophobic and hydrophilic monomers. The hydrophobic monomer is an alkyl substituted acrylamide or an acrylate ester. The hydrophilic monomer is an acrylamido sulfonic acid, an acrylamido disulfonic acid, or a styrene sulfonic acid.
PCT Publication WO 9966004, Dec. 23, 1999, discloses methods of using an aqueous composition containing a water-soluble or water-dispersible synthetic polymer which comprises a polymer formed by polymerizing (A) a hydrophobic monomer selected from the group consisting of an alkyl substituted acrylamide and an acrylate ester; and (B) a hydrophilic monomer selected from the group consisting acrylamido sulfonic acids and a styrene sulfonic acid. Optionally (C) monomers may be incorporated, including vinyl monomers such as vinyl acetate, N-vinyl-2-pyrrolidinone, N-vinyl caprolactam, 4-vinyl pyridine, and styrene.
D. G. Peiffer et al, Polymer, 29, 716, 1988 (xe2x80x9cSynthesis, solution viscosity and interfacial properties of random copolymers spanning a broad range of anionic characterxe2x80x9d) discloses polymers of styrene and Na-AMPS and discusses their solubility and viscosity behavior in various solvents including water.
Polymeric anti-misting additives reduce the misting of machine fluids at the source by stabilizing them against break-up during the extreme shear conditions which occur during metal working and similar operations. High molecular weight poly(ethylene oxide) is commonly used in this application. A typical polymer is POLYOX(copyright) available from Union Carbide. Typically, these polymers have a molecular weight from 1 to 2 million. However, these polymers are susceptible to shear. Metal working application often involve high shear, and as a result, metal working fluids containing high molecular weight poly(ethylene oxide) often suffer in performance when subjected to shear. Such degradation results when high shear conditions cause high molecular weight poly(ethylene oxide) to break down and lose its ability to suppress mist formation. In such high shear applications, the polymer must be replenished frequently.
The present invention, therefore, among other advantages, solves the problem of providing a water-soluble anti-mist additive for metal working fluid compositions and other high shear applications, which is resistant to degradation by shear. In one embodiment, the additive imparts properties to the composition such that the resultant composition sustains a shear rate range of from about 1 to about 1,000,000 sxe2x88x921, and sustains a shear stress range of from about 1 pascal to about 500,000 pascals. The word xe2x80x9csustainxe2x80x9d or xe2x80x9csustainsxe2x80x9d as used herein means that the compositions of the present invention have the ability to survive a shear rate range of from about 1 to about 1,000,000 sxe2x88x921 and a shear stress range of from about 1 pascal to about 500,000 pascals over a period of time in a spraying application, beginning at a point before the composition is discharged and ending at the moment the composition is discharged. The word xe2x80x9csurvivexe2x80x9d means the composition maintains its mist control properties from the point before discharge to the point after discharge such that effective mist control is achieved. The phrase xe2x80x9ceffective mist controlxe2x80x9d means that about 10% to about 100% mist reduction is achieved by the composition during and after discharge.
High shear applications other than metal working applications which can benefit from the present invention include applications of inks and coatings by spray and other technologies; application of deicing or anti-icing compositions; use of hydro-metallurgy/electro-winning compositions; use and application of cleaner compositions, such as household or industrial cleaner compositions; application of adhesive compositions; application of fire extinguishing compositions; application of personal care product compositions, including hand lotions, body creams, soaps, suntan lotions, hair conditioners, aftershave lotions, lip balms, cold creams, bubble bath, cleansing lotions, hairspray, deodorants, and perfumes; application of textile finish compositions, such as textile knitting fluid compositions or fiber finishing formulations; use of water-based hydraulic fluids; use of latex and other waterborne compositions; and dust control during mining operations.
The present invention provides a method for reducing mist formation in a high shear aqueous system which involves application of an aqueous composition to said high shear system, comprising: including in said aqueous composition, a water-dispersible, mist suppressing copolymer comprising
(A) hydrophobic monomer units comprising at least one ethylenically unsaturated hydrocarbon or such hydrocarbon having a hydrocarbyl substituent, said monomer units containing 3 to 30 carbon atoms; and
(B) hydrophilic monomer units comprising at least one polymerizable sulfonic acid or salt thereof.
The present invention further provides a method for lubricating a metal workpiece in a cutting operation, comprising: supplying to said workpiece a composition comprising (a) water and (b) a water-dispersible, mist suppressing copolymer comprising
(A) hydrophobic monomer units comprising at least one ethylenically unsaturated hydrocarbon or such hydrocarbon having a hydrocarbyl substituent, said monomer units containing 3 to 30 carbon atoms; and
(B) hydrophilic monomer units comprising at least one polymerizable sulfonic acid or salt thereof.
The present invention further provides an oil-in-water emulsion comprising water, oil dispersed therein, and the above copolymer.